Question: We-ve received letters from CMS regarding modifier 25. We use this modifier on the ED E/M when the physician performs an E/M visit and an EKG. Is this appropriate? Arizona Subscriber Answer: Carriers differ in their requirements for appending modifier 25 (Sig-nificant, separately identifiable evaluation and management service by the same physician on the same day of the procedure or other service) on diagnostic interpretations. Some carriers want you to append modifier 25 to your E/M code (such as 99281-99285) when the physician interprets an EKG (such as 93010, Electrocardiogram, routine ECG with at least 12 leads; interpretation and report only) in diagnostic cases. Best bet: Check with the insurer before filing claims with the EKG/modifier 25 combo. -- Reader Questions and You Be the Coder reviewed by Michael A. Granovsky, MD, CPC, FACEP, president of MRSI, an ED coding and billing company in Woburn, Mass.